Subjektive und objektive Bewertung von Maschinengeräuschen

The same magnetic tape recordings of a great number of noises produced by reciprocating combustion engines served as a basis for the evaluation of noises at two different places (Berlin, Stuttgart) using subjective noise measurements. The total sound pressure level was kept constant at 80 dB (head-phone was calibrated in free field, loudspeaker in free field).

The mean values of the measurements at Berlin and Stuttgart show a standard deviation of 2.4 dB ±2.1 dB.

The objective evaluation was made by measuring the sound levels in dB (A) and dB(B). The loudness was calculated following Zwicker from third octave spectra, and Stevens from the octave spectra. The value calculated according to Zwicker stands closest to the subjective mean values. The evaluation of the octave spectra by limiting curves (NR curves of ISO, “Geräuschstufe” of Lübcke) gives information, which deviates in some cases from the sound level in dB (A).